With annual exports in excess of $11 billion, the dairy sector is New Zealand’s biggest export earner (DairyNZ 2010), and there is significant emphasis by central government to increase the dairy sector earnings as a component of overall GDP. The dairy sector is fundamental to New Zealand’s economic growth, and therefore it is critical that the sector is able to anticipate and mitigate any emerging production and market-based risks. Climate change poses significant risks to and increased operating uncertainty for a sector dependent on consistent climatic conditions.

Three experiments were performed to determine the effects of combining urea and biochar together, in prills, on nitrous oxide (N2O) and/or ammonia (NH3) emissions from soil.

This project addressed an urgent need of the livestock industries for cost-effective methods of reducing methane emissions by ruminants grazing pasture. The predominance of pasture in the diet of ruminants in NZ presents some specific challenges for mitigation of methane production. A forage-based solution, while elusive to date, could provide a simple, cost-effective solution for a significant proportion of ruminant livestock in New Zealand.

Some prior studies conducted in the United Kingdom indicated that a high-sugar ryegrass would reduce methane production. Subsequently both a review article and modelling studies suggested mechanisms by which higher water soluble carbohydrate could influence the rumen environment and reduce methane.

This programme contributed to SLMACC Theme 2, Agriculture: “methane from ruminant animals and soils”. The project aims to determine if long-term hydrogen (H2) accumulation in the rumen, when rumen methanogens are directly inhibited, will have negative effects on rumen function and consequently animal performance. This knowledge needs to be established before mitigation strategies such as vaccination and small molecule inhibitors can be applied on farm. These technologies, currently being developed in PGgRc-funded programs¸ are especially suitable for NZ pasture based systems and removing potential barriers to their adoption will be of major benefit for reducing CH4 emissions.

Methane emissions from livestock comprise about 30% of New Zealand’s national total greenhouse gas emissions and New Zealand has played a pivotal role in spearheading ruminant methane mitigation research worldwide in both governance and science. At the forefront of this effort are several research programs that are attempting to inhibit specific methane producing microbes (methanogens) in the rumen.

The Emissions Trading Scheme (ETS) and the Permanent Forest Sink Initiative (PFSI)
were created by the New Zealand Government as part of a package of climate change
initiatives that will support New Zealand’s ratification of the Kyoto Protocol.

Shrublands cover large areas of New Zealand (Trotter et al. 2005) and often represent early- successional stages of regenerating tall forest. They establish spontaneously (with little or no capital investment) and relatively rapidly, and even where composed of exotic species they can act as effective nurse crops promoting tree establishment and succession to forest (Burrows et al. 2015).

Tree-pasture (TP) systems involving widely spaced planted trees on pastoral land have been a widespread feature of New Zealand’s pastoral hill country for 50+ years. The primary purpose of the trees is to reduce the occurrence of erosion processes to enable the continuation of livestock farming.

The Emissions Trading Scheme (ETS) and the Permanent Forest Sink Initiative (PFSI)
were created by the New Zealand Government as part of a package of climate change
initiatives that will support New Zealand’s ratification of the Kyoto Protocol.

Nitrification inhibitors have the potential to reduce nitrogen (N) loss from soils and increase N use efficiency. As the name suggests, nitrification inhibitors work by inhibiting the transformation of N via the nitrification pathway which results in prolonged ammonium retention in soils. Dicyandiamide (DCD) is an effective nitrification inhibitor to reduce N losses from soils, but DCD is susceptible to loss via biodegradation by the soil’s microbial community and leaching, downwards movement through soils that can be induced by rainfall. The purpose of this project is to develop calculation methods to estimate the effects of temperature and rainfall on DCD longevity in pastoral soils under field conditions.

Atmospheric emissions arising from the management of dairy farm manure are generally poorly understood and quantified. New Zealand’s greenhouse gas (GHG) inventory lists emissions from farm dairy effluent, predominantly in the form of methane, as a minor contribution to total dairy farm emissions. However, recent work indicates that for some emission pathways, like methane from effluent stored in ponds, emissions are substantially underestimated. Moreover, with increasing intensification of dairy farming and the handling of larger volumes of manure, dairy farm manure emissions are likely to increase at a disproportionally larger rate, compared with overall dairy farming emissions. It is therefore imperative to better understand the magnitude and special characteristics of emissions from dairy farm manure management. Furthermore, a number of practical mitigations technologies for these emissions exist; hence, a better understanding of these emissions could enable some moderate, but cost-effective GHG emission reductions in the dairy sector.

A purpose-built sampling and monitoring protocol is required to estimate soil organic carbon stocks (SOCS) and stock changes in hill country. It must provide information with accuracy and precision at spatial and temporal scales that matches the aim of the project.

Dicyandiamide (DCD) is a nitrification inhibitor that has been used in New Zealand’s agriclutural systems to reduce nitrate leaching and nitrous oxide (N2O) emissions. The efficacy of DCD at reducing both nitrate leaching and N2O can vary with season and soil type. One reason for this is the variation in seasonal soil temperature, since biological degradation of DCD is influenced by temperature. Other possibilities included the level of organic matter in the soil and the degree of soil aeration. Few studies have examined how soil organic matter influences DCD degradation while no studies have performed controlled experiments to determine the effect of soil aeration on DCD.

A review of the DCD literature is covered with respect to studies examining the use, loss and degradation of DCD when applied to agricultural systems. It has been mooted that the loss of DCD to waterways could potentially cause a build-up of ammonia thereby potentially harming aquatic ecosystems.